Thin wafer shipper

ABSTRACT

An improved wafer support mechanism in a wafer container useful for carrying a plurality of axially aligned thin mostly circular wafer substrates. The container includes a cassette that has a plurality of adjacently disposed teeth for receiving the substrates, wherein each rib member is continuous from the cassette open top to the cassette open bottom, a removable top cover portion, a removable bottom cover portion, a cushion assembly removably attached to the container top cover and another cushion assembly removably located in the container bottom cover and held in place by the weight of the wafer cassette. The top cushions are formed of individual segments having an extended lead-in feature at the end of each segment, spring sections in each segment and each segment has a V-shaped cross section to receive the wafer edge. The top and bottom cushions are installed in the top and bottom container covers respectively, and extend the wafer support to approximately the entire circumference of each wafer.

RELATED APPLICATIONS Priority Claim

The present application is a National Phase entry of PCT Application No.PCT/US2011/028243, filed Mar. 11, 2010, which claims priority from U.S.Provisional Application No. 61/312,718, filed Mar. 11, 2010, thedisclosures of which are hereby incorporated by reference herein intheir entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to containers for carryingsubstrates and semiconductor wafers, and the like. More particularly,the present invention relates to an improved wafer support mechanism ina wafer container useful for carrying a plurality of axially alignedthin mostly circular wafer substrates. The container includes a cassettethat has a plurality of adjacently disposed rib members for receivingthe substrates, wherein each rib member is continuous from the cassetteopen top to the cassette open bottom, a removable top cover portion, aremovable bottom cover portion, a cushion assembly removably attached tothe container top cover and another cushion assembly removably locatedin the container bottom cover and held in place by the weight of thewafer cassette.

BACKGROUND OF THE INVENTION

For years, manufacturers have produced special containers fortransporting and storing substrates and semiconductor wafers, and thelike. Due to the delicate nature of the wafers and their extreme value,it is vital that they are properly protected throughout thetransportation process. Since the handling of wafers is generallyautomated, it is necessary for wafers to be precisely positionedrelative to the handling equipment for the robotic removal andinsertion.

In addition to protection from damage by breakage, always in shippingstoring or processing semiconductor wafers, cleanliness andcontamination control is critical. The components and materials utilizedmust be very clean in the sense of not shedding or minimal shedding ofparticles and not exuding contaminants, such as gases, that can formfilm layers on the wafers. The containers and components are typicallyreused and must be amenable to cleaning and must be able to withstandrepeated washing and drying cycles. Additionally, it is also critical,due to the commodity nature of wafer containers, particularly shippersfor 100 mm and 150 mm wafers, that the containers are inexpensivelymanufactured and inexpensively maintained, such as replacement ofcomponent parts.

Conventional wafer shippers, particularly for 100 mm and 150 mm waferscomprise a wafer cassette, which holds a plurality of semiconductorwafers, contained in a wafer cassette container. The combinationprotects the wafers from mechanical damage and contamination during thestorage and transportation. See for example, U.S. Pat. Nos. 4,949,848;4,966,284; 4,793,488; and 5,273,159 for exemplary prior art wafershippers. These patents are owned by the owner of the instant inventionand are incorporated by reference herein.

The conventional wafer cassette is a single molded part generallycomprising a front end having an H-bar machine interface portion, a backend having a panel, and sidewalls having slots comprising lower curvedor converging portions following the curvature of the wafers, and withan open top and open bottom such as the device disclosed in U.S. Pat.No. 5,782,362 hereby fully incorporated herein by reference.

See element no. 1 in FIG. 12 of said reference. Also see U.S. Pat. No.4,949,848 owned by the owner of the instant invention. The open bottomof such cassettes are defined by the side walls that extend downwardlyfrom the converging portions in a parallel and vertical arrangement, andby the feet that extend downward from the sidewalls. The feet aregenerally planar, parallel, and with parallel edge surfaces upon whichthe carrier rests when it is seated with the open top upward. The edgesurfaces will typically have an industry standard locating notch forengaging with a cooperating rib on a seating surface for properpositioning and forward rearward securement.

Such conventional cassettes generally have standardized dimensions,features, and configurations so as to be relatively interchangeable anduseable with robotic processing equipment from a variety ofmanufacturers. This includes the H-bar and the parallel elongate feetwith the notches. Additionally, for example, the “pitch”, or distancebetween the same surface of wafers stored in adjacent slots, istypically 0.1875 inch, while the depth of the slot at each sidewall istypically 0.440 inch.

The wafer cassette container or container portion of the shipperincludes a lower base portion and a separate top cover portion havingcushioning features for protecting the wafers during shipment. Someshippers, designed typically for 200 mm wafers or larger, include abottom cushion secured to the base portion, see U.S. Pat. No. 5,273,159,for example. The cassette may conventionally be loaded robotically usingthe cassette oriented such that the H-bar side is positioned at thebottom of the cassette. The H-bar then functions as a machine interfaceto properly seat the cassette on an equipment surface so that wafers maybe robotically inserted with the wafers in a horizontal plane into theopen front of the cassette. The loaded cassette is then rotated 90degrees such that the wafers are in a vertical plane and the loadedcassette is placed into the lower base portion of the wafer carriercontainer. Such conventional wafer carrier containers may have alocation ribs in the bottom at a seating surface to cooperate with thelocating notches on one or both of the feet to properly orient and seatthe cassette.

Recently, the semiconductor industry has begun using wafers having avery thin cross sectional dimension. The thickness of these thin siliconwafers can be as thin as 200 um, in contrast with a typical conventionalSEMI standard wafer thickness. Also, a thin germanium wafer thicknesscan be 125 um. Thin wafers present unique design considerations, andcassette style shippers are unsatisfactory in several respects for usewith the thinner wafers. Thin wafers can be considered any waferthickness that is less than the SEMI standard nominal thickness forwafers which is shown in the following table.

Wafer Standard Diameter Wafer Standard Thickness 100 mm 525 um 125 mm625 um 150 mm 675 um 200 mm 725 um 300 mm 775 um 450 mm 925 um

Another characteristic of thin wafers is that they can be substantiallymore fragile and prone to physical damage than a standard wafer. Aconventional wafer carrier having limited support for the wafer aroundthe extreme periphery of the wafer, causes increased stresses duringshock events. The stress created makes the wafer even more prone tophysical damage from shock or vibration.

The edges of thin wafers can be very sharp, and are formed from veryhard materials, like silicon and germanium. These sharp edges can getcaught on the cushion when the cover is installed causing cross-slottingand potentially causing damage to the wafer. Additionally, thin wafersmay cut through softer materials that come into contact with theperipheral edge of the wafer, for example the wafer carrier plasticmaterial.

Although existing containers are designed to reduce the effects ofphysical shock which can damage thin and fragile wafers, wafercontainers are needed with improved shock reducing properties. There isa need for a wafer carrier specifically designed to be suitable for usewith very thin wafers, in particular to accommodate their increasedfragility while maintaining low manufacturing cost.

SUMMARY OF THE INVENTION

The invention as depicted is an embodiment of an improved wafercontainer for use in transporting, storing or processing thin datasemiconductor wafers or other thin substrates. The present inventioncomprises generally a cassette portion and a container portion. Thecassette portion wafer cassette is a single molded part generallycomprising a front end having an H-bar machine interface portion, a backend having a panel, and sidewalls having slots comprising lower curvedor converging portions following the curvature of the wafers, and withan open top and open. Parallel feet portions extend downwardly from thebottoms of the converging portions and present feet edge surfaces.

This cassette is placed into a two-piece container portion fortransport. This container portion comprises a top cover which attachesto a bottom cover. The top and bottom covers also include a cushionassembly which is designed to ensure that the wafers do not cross-slotand that they are sufficiently held in place during transportation toavoid damage. The top cover wafer retaining cushion assembly isremovable and is formed so that it contacts the edge periphery of thewafer from the top of the side wall ribs on one side of the cassette tothe top of the side wall ribs on the opposite side of the cassette. Thisupper cushion includes spring features, configured as U-shaped sections,on each rib section near each side of the cushion assembly that providecontrolled compressive force to the wafers to prevent wafer rotationduring transit and shipping. This upper cushion also contains anextended tooth guide-in portion segment, configured as a prong, on theend of each rib section at the sides of the cushion assembly. Uponplacement of the top cover onto the base portion the wafer edges firstencounter and possibly engage the wafer guides to prevent the wafersfrom cross-slotting. Wafer cross-slotting is defined as the conditionwhere a wafer locates in a top cushion and in the adjacent lower cushionof between cushion segments. The bottom cover also includes a removablewafer retaining cushion assembly. This cushion assembly is formed sothat it contacts the edge periphery of the wafer from the bottom of theside wall ribs on one side of the cassette to the bottom of the sidewall ribs on the opposite side of the cassette. The bottom cushion maysimply of the side wall ribs on the opposite side of the cassette. Thebottom cushion may simply sit in a conforming region in the bottom ofthe cassette without being secured therein other than by gravity, thatis, the bottom cushion may be constrained only by gravity from upwardlinear vertical movement. The bottom cushion has rails extending in anaxial direction from which the arcuate wafer cushion segments aresuspended. The bottom cushion rails may have pads extending laterallyand that contact the upward seating surface of the base portion. Thefeet of the cassette portion may seat on these pads such that the padsare sandwiched between base portion and cassette portion.

The result of the side wall ribs together with the top and bottom covercushion assemblies is to support each wafer in the container on a largerportion of the circumference of the wafer thereby reducing the stresspoints created where the previous wafer cushions contacted the waferedge. The wafer is suspended away from the slots in the sidewalls whenenclosed in the container portion. However, the gap may be 0.005-0.015inches and may permit contact with the sidewalls at the grooves whenunder an impact condition.

An advantage of embodiments of the invention is that the cassette, thetop cover, the bottom cover, the two wafer cushions may be formed of thesame polymer material, such as polypropylene. This makes identifyingcontamination issues associated with wafers carried in the containermuch easier as there is only one material to investigate as the possiblecontaminant source with respect to the shipper.

An advantage of an embodiment of the present invention is a wafercontainer for carrying a plurality of axially aligned thin semiconductorwafers. The container has a cassette portion with side wafer supportsthat cooperate with the cushion assemblies in the top and bottom coverto support thin wafers for short term storage and transportation.

Another advantage of an embodiment is the cushion design includes aspring mechanism that provides compressive force to the wafers toprevent rotation during transit/shipping

Another advantage of an embodiment is the cushion design includes analignment feature at the edges of the upper cushion to prevent wafercross-slotting.

Another advantage of embodiments of the invention is that the lowercushion is seated in the bottom by simply placing the cushion therein ina conforming recess. Additionally in embodiments, the cushion has a pairof horizontal rails extending in an axial direction with respect to thewafers, with a plurality of wafer cushion segments extendingtherebetween. The rails may have pads extend therefrom that aresandwiched between the wafer cassette portion feet and the base portion.Thus the lower wafer cushion, in certain embodiments, provides directengagement and cushioning to the wafers as well as providing cushioningthe cassette portion.

Additional objects, advantages, and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a wafer shipper according to theinvention herein.

FIG. 2 is an exploded view of a wafer shipper according to the inventionherein.

FIG. 3 is a cross section view of the wafer shipper of FIG. 1 accordingto the invention herein.

FIG. 4 is a top perspective view of the base portion of the shipper ofFIG. 3.

FIG. 5 is a top perspective view of the lower wafer cushion to be seatedin the base portion.

FIG. 6 is a perspective view of the bottom side of the wafer cushion ofFIG. 5.

FIG. 7 is a cross sectional view of the wafer cushion of FIGS. 5 and 6.

FIG. 8 is a cross sectional view taken at line 8-8 of FIG. 7.

FIG. 9 is a top perspective view of the base portion with the wafercushion seated therein.

FIG. 10 is a front elevational view of the assembled shipper withportions broken away to disclose the pad of the wafer cushion sandwichedbetween the base portion and the wafer cassette foot.

FIG. 11 is a top perspective view of a wafer cushion suitable for thetop cover and in accord with the invention herein.

FIG. 12 is a bottom perspective view of the wafer cushion of FIG. 11.

FIG. 13 is a cross sectional view through the wafer cushion of FIGS. 11and 12.

FIG. 14 is a cross sectional view taken at line 14-14 of FIG. 13.

FIG. 15 is a perspective view of the inside of the top portion of thecontainer portion with a cushion therein.

FIG. 16 is a cross sectional detail showing the attachment structure ofthe wafer cushion and the top cover portion of FIG. 15.

FIG. 17 is a schematic view of a wafer constrained by the inventionsherein.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a wafer shipper 20 according to embodimentsof the invention is illustrated and is comprised generally of acontainer portion 22 comprising a base portion 24, a top cover portion28, a cassette 30, a lower cushion 34, and an upper cushion 38.

The present invention provides for the substrate cushion assemblies tobe mounted in the cover portion 28 and the base portion 24 of the wafercontainer portion 22. These cushion assemblies provide additionalsupport to the wafer W during transportation to minimize wafer damagefrom shock and vibration and rotation without adding additionalsecondary packaging. When the container top cover is installed, theadditional wafer cushion assemblies also are able to guide the wafersinto the optimum seating position inside the cassette to reduce the riskof the wafers cross-slotting during the loading operation and transit.The upper and lower peripheries of the wafers are in contact with centerlines of respective V shaped grooves 49 in the upper cushion segments 50and the V shaped groove 40 in the lower cushion segment so that each ofthe wafers is kept apart from its neighbor wafer, thus reducing thecontact of wafers, thereby minimizing contamination of the wafersurface. Further, the elastic resilience of the cushion assembly servesto ensure correct positioning of the wafers when the upper periphery ofthe wafers contacts the cushion, the elastic cushion is bent archwise toeffect movement of the periphery of the wafer into the center line ofthe V-shaped grooves 49, 40. The elastic resilience of the cushionassembly exhibits a damping effect to the vibrations and mechanicalshocks on the wafers during transportation of the wafer container sothat the wafer contained therein can be protected from damage. Existingcushion technology demonstrates wafer damage at a force of 25 g, in a 38inch free-fall drop and testing of the present invention cushionassemblies indicates wafer damage at a force of between 46 g and 51 g ina 38 inch free-fall drop.

Referring to FIGS. 3-10, details of the bottom base portion 24 of thecontainer portion 22 and the wafer cushion are illustrated. Thecontainer has an axial direction consistent with the axis a of wafers inplace in the cassette that is placed in the container. In thisembodiment, the wafer cushion is configured as a panel, that it, thereis not separation between individual wafer engagement portions orsegments 56. The cushion has a pair of rails 58 that provide structuralsupport for the arcuate wafer engagement portions 56. Extending from thelower edge portion 58 of the rails are tabs or pads 62 with leg portions63. The pads have a bottom surface 64 that contacts the seating surface66 of the bottom floor 68 of the base portion 24. The bottom floor ofthe base portion has a cushion receiving area 70, configured as anaxially extending gutter 71, which conforms to the cushion andparticularly the rails of the cushion. That is, recessed areas 72 allowthe cushion to be essentially dropped into place and it properly seats.The rails also have notches 74 that further cooperate with locating ribs76 recessed area of the base portion. The rails further facilitate thevery easy placement of the cushion. Notably there is no furtheroperation in installing the bottom cushion other that dropping it inplace.

Also, the bottom portion has a four walls 82 with two end walls 84 andtwo side walls defining the enclosure. Two angled or inclined wallportions 86 with inclined surfaces 88 that further aid in guiding thebottom cushion into proper seating position.

The base portion also receives and is conformingly shaped for thecassette 30. The cassette has a pair of sidewalls 92 connected with endwalls 93 and 94. The sidewalls have vertical upper portions 95 andconverging lower portions 96 and ribs or teeth 98 that define slots 100.Extending downwardly from the bottom edge 102 of the converging wallportions are a pair of feet 106 with edge portion 108 and edge surfaces110. The feet have locating notches 112. The cassette sits on the feetwhen the open top is oriented upwardly. The cassette has an open top 113and an open bottom 114. Often for robotically loading and unloading suchcassettes, the cassette will be rotated forward 90 degrees and rest onthe conventional H-bar 116 such that wafers may be loaded and unloadedhorizontally.

The recessed area 70 and the inclined surfaces 88 further provideguidance for the feet of the cassette 30 when lowered into the baseportion. The cassette is placed in the base portion after the lowercushion 34 is placed therein. The feet are guided into the cassettereceiving region 116 which is in the gutter 71 laterally outside of therails of the cushion. The lower edges, in certain embodiments, ratherthat seat on the surface of the floor, seat on the pads 62 of the lowercushion as best illustrated in FIG. 10. The pads are sandwiched betweenthe cassette and base portion provide stability and also providing thecassette with enhanced shock absorption due to the additional layer andthickness of polymer.

Moreover, the cassette as well as the cushion as described above,utilize the locating rib 76 on the floor of the base portion for properpositioning and for securement of the cassette in the forward/rearwardor axial direction. Conventionally these ribs are utilized for locatingand stabilizing the positioning of wafer cassettes on equipment or incontainers, but not for positioning cushions. Utilizing the rib forpositioning the cushion and the cassette, particularly as in certainembodiments herein where the lower cushion is not secured or attached tothe base portion, assures proper cooperation and alignment to preventmisalignment or cross slotting of wafers and the associated damage.

Referring to FIGS. 3 and 11-16, details of the upper cushion 38 and topcover portion 28 are illustrated. The upper cushion has a plurality ofelongate wafer engaging segments 50 that are arcuate shaped to followthe periphery of the wafer and have at the segment end portions 130springs 134 configured as U-shaped polymer springs that connect tosupport rails 140. The rails have inwardly extending recesses 144 thatattach to tabs 148. The upper cushion, in certain embodiments, needs tobe compressed in the directions indicated by arrows 160 in order toinstall the cushion on the top cover portion. Lateral rails 164conveniently function as a handle as well as functioning as an ejectorpad for ejection pins to eject the part from the mold during theinjection molding process. Extending downwardly from the support rails140 are wafer guides configured as prongs 170. The prongs are elongateand tapered and are the first part of the top cover encountered by thewafers when the top cover portion is lowered onto a cassette seated in abase portion. The prong has a length d1, measured in a radial direction,at least two times the depth of the V-shaped grooves 49 of theassociated wafer segments 50. According to embodiments of the invention,when upper cushion 38 is secured to the inside of top cover portion 28,prongs or guides 170 of upper cushion 38 extend radially inward at least5 mm from the peripheral edge of a 100 mm wafer seated in cassette 30,for example. The prong has a width dimension in a direction parallel tothe elongate direction of the wafer segments that is at least twice thewidth of the prong in the normal direction transverse to the elongatedirection of the wafer segments that is a multiplier of at least 2. Inother embodiments the multiplier is at least 1.5; in other embodimentsthe multiplier is at least 2.5. The prongs are positioned to beintermediate each of the slots as defined by the teeth of the wafercassette and also defined by the V-shaped grooves of the cushions.According to one embodiment, the maximum radial distance that the guidesextend inwardly from edges of wafers held therein is within 20% of themaximum radial distance from the edges of the wafers that the teethextend inwardly.

In use, the cassette is typically loaded with the open top rotatedforwardly. The cassette then is rotated rearwardly to put the open topback on top. The cassette is lowered into the base portion with thelower cushion already in place in the base portion. As the base portionreceives the loaded cassette, the lower peripheral edge 174 of thewafers engage the arcuate wafer engagement portions 56 on the lowercushion. The cushion is configured then to slight raise the wafers offof the lower edge portion 176 slightly to provide a gap 179 between thelower edge portion 176 and the wafer W when the cassette is seated inthe base portion. In certain embodiments the gap might be a fewthousandths of an inch. For example 0.005 inches to 0.020 inches. Or,0.002 inches to 0.050 inches. The gap is substantially greater in theslot above the lower edge portion and the gap increases as the distancefrom the lower edge portion increases. Then the top portion 28 then islowered over the cassette with the guides 170 interlaced inbetween thewafers as the top portion is lowered. When the top cover is fullyengaged with the bottom cover, the upper cushion engages the topperipheral edge 183 of the wafers at the arcuate wafer engagementsegments. The arcuate wafer engagement portions position the wafersspaced from the guides and further providing a gap at the outer nonspring loaded portion or segment 185 of the cushion that isapproximately the same as the gap between the lower edge portions of theslots and the wafers. In certain embodiments the gap might be a fewthousandths of an inch. For example 0.005 inches to 0.020 inches. Or,0.002 inches to 0.050 inches. The non spring loaded portion 185 is atthe portion of the upper cushion that engages the attachment features ofthe inside of the top cover.

Referring to FIG. 17, in a fully loaded and closed state, the wafers areperipherally supported and suspended between arcuate portions of theupper cushion located at top dead center of the wafers and arcuateportions of the bottom cushion located at bottom dead center of thewafers. The arcuate engagement portions provide compressive forceindicated by the arrows 221, and each extend around and engage thewafers over an arc 210 of approximately 55 degrees in one embodiment. Inan embodiment the arcuate engagement portions each extend around andengage the wafers over an arc 210 of from 50 degrees to 60 degrees. Orabout 49 degrees to about 61 degrees. In a shock condition furtherperipheral, more rigid peripheral support 216 is provided at positionsspaced from the arcuate portions. At the lower periphery of the wafer,the more rigid support has a spacing 220 of about 5 degrees from theends of the cushion and is provided by the lower edge portions of thegrooves. At the upper peripheries of the wafers, the more rigid supporthas a spacing 222 of about 5 degrees from the ends of the cushions andprovided by the non spring loaded portion of the upper cushion proximatethe support rail of the cushion. The more rigid supports at both theupper peripheries of the wafers arc 226 along the wafer of from 4degrees to 10 degrees or more. “Peripheral support” when used hereinmeans support on the exterior peripheral surface of the wafer and/or onthe peripheral portion of the corners between the opposing planarsurfaces of the wafer, for example, the support provided by V-shapedgrooves. Support extending over the surfaces of the wafers and directlyintermediate the wafers which may be helpful in a axial shock conditionis provided conventionally by the wafer teeth 230 as indicated by theportions outlined in dash lines, but is also now provided by the guidesor prongs 232 in substantial vertical alignment and shown by dash dotlines.

Then in a shock condition, the wafers may move within the suspensionprovided by the arcuate suspended wafer engagement portions. During suchmotion, the lower edge portions 176 of the wafer slots may engage theouter non spring loaded portion of the 185 of the upper cushions.Moreover, further support is provided by the guides 170 that extendinbetween the wafers, generally precisely between the wafers. The guidesprovide a surface support on impact that is substantially a mirror imageor similar to the surface support on impact provided by the teeth of thecassette. The further engagement of the wafers during shock conditionslimit the amount of flexing of the brittle wafers. This mirror imagesurface support is provided and provides enhanced protection for thinwafers under greater loading than is provided in conventional shippers.“Surface” support herein means support provided at the periphery of thewafer by a surface that forms an angle with surface of the wafer of notmore than 35 degrees.

Thus during non shock conditions the wafers are supported at arcsextending about 55 degrees at the top and bottoms of the wafers.Further, more rigid support under a shock condition is provided isprovided peripherally

Referring in particular to FIG. 3, a novel suspension is provided suchthat in a non impact condition, the wafer is supported by the lowercushion 34 at the arcuate wafer engagement portions 56. T

The components herein are conventionally manufactures by injectionmolding. A suitable material is polypropylene. Other polymers will alsobe suitable.

Referring to the figures and particularly FIG. 3, a horizontallyextending and continuous upper edge portion 190 of the base portionpreferably extends upwardly to a level that is a distance of at least25% of the height of the wafer cassette. Similarly, a lower continuoushorizontal edge portion 192 of the top cover portion extends down to alevel below the top of the cassette a distance that is at least 25% ofthe height of the cassette. The upper edge portion engages and latchesto the cooperating lower horizontal edge portion 192 of the top cover.The edge portions mate to form a surface continuous around the peripheryof the container portion with recesses 195 for operating the latches.The juncture 196 of the top cover to the bottom base portion extendsentirely around the midsection 197 of the wafer cassette. The structuresand features of similar containers are illustrated in U.S. Pat. Nos.4,949,848; 4,966,284; 4,793,488; and 5,273,159 and such structures andfeatures are suitable for use with the inventions described herein.These patents are owned by the owner of the instant invention and areall incorporated by reference herein. Notably the container portionsdescribed herein have only one side suitable for seating on a horizontalsurface. That is they do not have seating features on adjacent sideslike H-bar cassettes and certain containers know as FOSBs (front openingshipping boxes) that are utilized typically for larger diameter wafers,specifically 300 mm or larger. In embodiments of the invention, each ofthe top cover portion and base portion have a height, and the height ofeach is within 25% of the height of the other.

When “substantially” is utilized herein with reference to a dimension ordistance, it means within 15% of the compared to dimension.

The embodiments above are intended to be illustrative and not limiting.Additional embodiments are within the claims. Although the presentinvention has been described with reference to particular embodiments,workers skilled in the art will recognize that changes may be made inform and detail without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A wafer shipper comprising a cassette and acassette container and configured for holding thin wafers, the cassettecomprising a pair of sidewalls defining slots for holding wafers, a pairof endwalls extending between the sidewalls, one of the endwallsconfigured as an H-bar machine interface, and pair of elongate feetextending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion that seats in a receiving region in thebottom base portion; wherein the upper cushion is secured to the insideof the top cover and the upper cushion has a pair of rails that attachto the top cover, and that support a plurality of wafer engagingsegments, the wafer engaging segments connecting to the pair of rails byway of a respective pair of U-shaped springs formed of the same materialas the wafer engaging segments, the upper cushion further comprising aplurality of guides extending radially inward for placement in betweenwafers secured by the wafer engaging segments.
 2. The wafer shipper ofclaim 1 wherein the base portion has a locator rib extending from afloor of the base portion, and wherein at least one of the cassette feethas a lower edge portion, the lower edge portion having a notchpositioned to seat on the locator rib when the cassette is placed in thebottom base portion, and wherein the lower cushion has a pair of railswith wafer engagement portions extending therebetween, the rails eachhaving a lower edge portion and at least one of said lower edge portionsof the rails having a centrally positioned notch positioned to also seaton the locating rib.
 3. The wafer shipper of claim 1 wherein the lowercushion comprises a pair of rails supporting a plurality of waferengagement portions, and wherein the lower cushion further comprises aplurality of pads extending laterally out from the pair of rails, andwherein the lower cushion seats on a floor of the base portion by way ofthe plurality of pads.
 4. The wafer shipper of claim 3 wherein each ofthe pads has a top surface and when the cassette is positioned in thebase portion the feet of the cassette seat on top of the pads wherebythe pads are sandwiched between the base portion floor and the cassette.5. The wafer shipper of claim 1 wherein the upper cushion is secured tothe inside of the top cover and the guides of the upper cushion areconfigured as prongs that extend radially inward at least 5 mm from theperipheral edge of a 100 mm wafer seated in the cassette.
 6. The wafershipper of claim 1 wherein the lower cushion is secured to the inside ofthe bottom base portion and the lower cushion has a pair of rails thatsupport a plurality of wafer engagement portions.
 7. The wafer shipperof claim 1 wherein the upper cushion has V-shaped grooves for receivingthe periphery of the wafers, the V-shaped grooves defining wafer slots,the guides of the upper cushion configured as a plurality of prongs eachpositioned intermediate the slots defined by the V-shaped grooves. 8.The wafer shipper of claim 1 wherein the wafer engaging segments eachhave a V-shaped groove with a maximum depth, the V-shaped grooves forreceiving the periphery of the wafers, the guides of the upper cushionconfigured as a plurality of prongs each positioned intermediate slotsdefined by the V-shaped grooves and positioned to be the first part ofthe upper cushion to confront the wafers when the top cover is installedon a base portion with a cassette loaded with wafers therein.
 9. Thewafer shipper of claim 8 wherein each of the prongs extends radiallyinward from the periphery of the wafer when the top cover is fullyseated on the bottom base portion, a distance at least twice the maximumdepth of the V-shaped grooves.
 10. The wafer shipper of claim 1 whereinthe lower cushion seats in the bottom base portion and is constrainedfrom vertically upward linear movement only by gravity when the cassetteis not seated.
 11. The wafer shipper of claim 1 wherein each of thecomponents are formed of polypropylene.
 12. A wafer shipper comprising acassette and a cassette container, the cassette comprising a pair ofsidewalls defining slots for holding wafers having a circular periphery,a pair of endwalls extending between the sidewalls, one of the endwallsconfigured as an H-bar machine interface, and pair of elongate feetextending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion received in the bottom base portion, theupper cushion being secured to the inside of the top cover and the uppercushion has a pair of rails that attach to the top cover and thatsupport a plurality of wafer engaging segments, each wafer engagingsegment traversing between the two rails and having a length and havinga V-shaped groove with a depth, the V-shaped groove extending the lengthof the segment, the upper cushion further having a plurality of guidespositioned proximate ends of the wafer engaging segments, the guidesextending radially inward for placement in between wafers secured by thewafer engaging segments, the guides being spaced circumferentially alongthe wafers from the wafer engaging segments and having a length in aradial direction with respect to wafers in the container that is atleast 2 times the depth of the V-shaped grooves, the guides providing asurface for the wafers in a shock condition.
 13. A wafer shippercomprising a cassette and a cassette container, the cassette comprisinga pair of sidewalls defining slots for holding wafers, a pair ofendwalls extending between the sidewalls, one of the endwalls configuredas an H-bar machine interface, and pair of elongate feet extendingdownwardly from the respective sidewalls; the cassette containercomprising a bottom base portion for receiving the cassette therein, anda top cover attachable to bottom base portion, each of the top cover andbase portion having four walls and a common wall spanning between thefour walls, each of the top cover and base portion having a juncture forclosing the top cover to the base portion, the cassette containerfurther comprising an upper cushion attachable to the top cover and alower cushion received in the bottom base portion, the upper cushionbeing secured to the inside of the top cover and the upper cushion has apair of rails that attach to the top cover and that support a pluralityof wafer engaging segments extending therefrom, the wafer engagingsegments each having a V-shaped groove, the upper cushion furthercomprising a plurality of tapered guides, each with a tip, extendingdownwardly from the rails and in radial alignment with a location wherethe rails attach to the top cover, the tapered guides each positionedsuch that tips of the guides move past the periphery of the wafersbefore the wafer peripheries enter the V-shaped grooves and such thatthe tapered guides are closer, along the circumference of the wafers, tothe sidewalls of the cassette than the V-shaped grooves are to thesidewalls of the cassette, wherein the tapered guides are eachpositioned intermediate the slots and positioned to be the first part ofthe upper cushion to confront the wafers when the top cover is installedon a base portion with a cassette loaded with wafers therein.
 14. Awafer shipper comprising a cassette and a cassette container, thecassette comprising a pair of sidewalls defining slots for holdingwafers, a pair of endwalls extending between the sidewalls, one of theendwalls configured as an H-bar machine interface, and pair of elongatefeet extending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion received in the bottom base portion,wherein the upper cushion has rails that support a plurality of waferengaging segments, the wafer engaging segments connecting to the railsby U-shaped springs, and wherein the lower cushion comprises a pair ofrails supporting a plurality of wafer engagement portions, and whereinthe lower cushion further comprises a plurality of pads extendinglaterally out from the pair of lower cushion rails, and wherein thelower cushion seats on a floor of the base portion by way of theplurality of pads and each of the pads has a top surface and when thecassette is positioned in the base portion, the feet of the cassetteseat on top of the pads whereby the pads are sandwiched between the baseportion floor and the cassette, further wherein the lower cushion seatsin the base portion and is constrained from vertically upward linearmovement only by gravity when the cassette is not seated.
 15. A wafercushion for placement at the open top of an H-bar wafer cassette, thecushion having a plurality of separate and end supported arcuate waferengaging segments each having a V-shaped groove, a U-shaped springextending from each end of each wafer engaging segment, each U-shapedspring connecting to a rail portion, the rail portion providing a rigidarcuate wafer engagement surface that is radially spaced outward fromthe respective arcuate wafer engaging segments, each rail further havinga plurality of prongs extending radially inward for placement inbetweenwafers secured by the wafer engaging segments.
 16. A wafer shipperhaving an H-bar wafer cassette with an open top and opposing sidewalls,the sidewalls connected by opposing end walls, each sidewall having avertical upper portion and a converging lower portion, interior surfacesof the sidewalls defining a plurality of teeth with slots therebetweenfor holding axially aligned wafers, a cushion for placement at the opentop of the H-bar wafer cassette, the cushion having a pair of rails forattaching to a top cover of the wafer shipper, the pair of railssupporting a plurality of arcuate wafer engaging segments each having aV-shaped groove, each V-shaped groove having a height measured in aradial direction, the cushion further having a plurality of guidespositioned proximate ends of the wafer engaging segments, the guidesextending radially inward for placement in vertical alignment with theteeth of the cassette and the guides positioned to be spacedcircumferentially along the wafers from the V-shaped grooves and inradial alignment with a location where the rails attach to the topcover.
 17. The wafer shipper of claim 16 wherein the guides extendinwardly a maximum radial distance from edges of wafers held therein andwherein the teeth extend inwardly a maximum radial distance from theedges of the wafers held therein that is substantially the same as themaximum radial distance that the guides extend inwardly from the edgesof the wafers.
 18. The wafer shipper of claim 17, wherein the maximumradial distance that the guides extend inwardly from edges of wafersheld therein is within 20% of the maximum radial distance from the edgesof the wafers that the teeth extend inwardly.
 19. The wafer shipper ofclaim 16, wherein each of the teeth have a most lower portion and theguides are in vertical alignment with the most lower portion of theteeth.
 20. A wafer shipper comprising a cassette and a cassettecontainer and configured for holding thin wafers, the cassettecomprising a pair of sidewalls defining slots for holding wafers, a pairof endwalls extending between the sidewalls, one of the endwallsconfigured as an H-bar machine interface, and pair of elongate feetextending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion that seats in a receiving region in thebottom base portion; wherein the upper cushion is secured to the insideof the top cover and the upper cushion has a pair of rails that attachto the top cover, and that support a plurality of wafer engagingsegments, the wafer engaging segments connecting to the pair of rails byway of a respective pair of U-shaped springs formed of the same materialas the wafer engaging segments; wherein the wafer engaging segments eachhave a V-shaped groove with a maximum depth, the V-shaped grooves forreceiving the periphery of the wafers, the upper cushion having aplurality of prongs each positioned intermediate the slots andpositioned to be the first part of the upper cushion to confront thewafers when the top cover is installed on a base portion with a cassetteloaded with wafers therein.
 21. A wafer shipper comprising a cassetteand a cassette container and configured for holding thin wafers, thecassette comprising a pair of sidewalls defining slots for holdingwafers, a pair of endwalls extending between the sidewalls, one of theendwalls configured as an H-bar machine interface, and pair of elongatefeet extending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion that seats in a receiving region in thebottom base portion; wherein the base portion has a locator ribextending from a floor of the base portion, and wherein at least one ofthe cassette feet has a lower edge portion, the lower edge portionhaving a notch positioned to seat on the locator rib when the cassetteis placed in the bottom base portion, and wherein the lower cushion hasa pair of rails with wafer engagement portions extending therebetween,the rails each having a lower edge portion and at least one of saidlower edge portions of the rails having a centrally positioned notchpositioned to also seat on the locating rib.
 22. The wafer shipper ofclaim 21, wherein the upper cushion is secured to the inside of the topcover and the upper cushion has a pair of rails that attach to the topcover, and that support a plurality of wafer engaging segments, thewafer engaging segments connecting to the pair of rails by way of arespective pair of U-shaped springs formed of the same material as thewafer engaging segments.
 23. A wafer shipper comprising a cassette and acassette container and configured for holding thin wafers, the cassettecomprising a pair of sidewalls defining slots for holding wafers, a pairof endwalls extending between the sidewalls, one of the endwallsconfigured as an H-bar machine interface, and pair of elongate feetextending downwardly from the respective sidewalls; the cassettecontainer comprising a bottom base portion for receiving the cassettetherein, and a top cover attachable to the bottom base portion, each ofthe top cover and base portion having four walls and a common wallspanning between the four walls, each of the top cover and base portionhaving a juncture for closing the top cover to the base portion, thecassette container further comprising an upper cushion attachable to thetop cover and a lower cushion that seats in a receiving region in thebottom base portion; wherein the lower cushion seats in the bottom baseportion and is constrained from vertically upward linear movement onlyby gravity when the cassette is not seated in the bottom base portion;further wherein the lower cushion comprises a plurality of padssandwiched between the bottom base portion and the feet of the cassettewhen the cassette is seated in the bottom base portion.
 24. The wafershipper of claim 23, wherein the upper cushion is secured to the insideof the top cover and the upper cushion has a pair of rails that attachto the top cover, and that support a plurality of wafer engagingsegments, the wafer engaging segments connecting to the pair of rails byway of a respective pair of U-shaped springs formed of the same materialas the wafer engaging segments.
 25. A wafer shipper having a cassettewith opposing sidewalls, the sidewalls connected by opposing end walls,each sidewall having a vertical upper portion and a converging lowerportion, interior surfaces of the sidewalls defining a plurality ofteeth with slots therebetween for holding axially aligned wafers, acushion for placement at an open top of the wafer cassette, the cushionhaving a pair of rails for attaching to a top cover of the wafershipper, the pair of rails supporting a plurality of arcuate waferengaging segments each having a groove, each groove having a heightmeasured in a radial direction, the cushion further having a pluralityof guides positioned proximate ends of the wafer engaging segments, theguides in radial alignment with a location where the rails attach to thetop cover and the guides extending radially inward for placement inbetween wafers secured by the wafer engaging segments, the guides eachbeing closer, along the circumference of the wafers, to the sidewalls ofthe cassette than the grooves are to the sidewalls of the cassette.